text:
How should you deal with passenger throttle interference just after take-off?
I took a passenger on a flight recently in a C42, in which the throttle is placed between the legs. Shortly after take-off (I'm talking 100ft in the air at full throttle), the passenger tucked his legs backwards, taking the throttle with him (despite a pre-flight briefing of where critical controls lay).
In the moment, I reached across, grabbed his legs and pulled them forwards, this resulted in the stick taking itself off to the left and induced a heavy roll. I managed to free the throttle and get full power and level the wings again for a safe climb-out.
As you can imagine, this was a near-miss scenario that almost ended badly. On reflection, I think maybe I should have treated it as an engine failure and landed ahead in a field - but that would risk damage to a club aircraft.
SO my question is, what would the best course of action have been in this situation?

You managed to find the cause of the engine reving down, fix it, and continue your flight safely. So I'm pretty sure it was the best course of action. If you decided to land the plane safely in the field in front it would have been the best course of action too. You made a quick jugement and it payed off. That's what matter in my opinion...

Your hand should never leave the throttle during climb out, certainly not below circuit height.

@Jamiec just to be clear (as I didn't mention it), it didn't. But his 2 legs overpowered my one hand...

Jeez I'd totally forgotten the absurd controls arrangement of the C42...

I went for a test flight in a C42 with a view to buying a share.  I too was pretty confused about the position of the throttle and given that I was likely to take my 5yr old nephew for a flight, wondered if it would be problematic.  I did note, however, that it could be folded up in such a way that it was unlikely to be accidentally moved.  I'm not sure if that is the case with all C42s, but maybe worth a look.

@MickWaites it was folded during this incident :)

So colour me confused; how was it both "folded down" and also in your hand at all times? One seems to contradict the other.

@Jamiec Look up the throttle of the aircraft in question. There are two throttle controls, one between the legs of each occupant. The top portion folds down, but the lower arm of the throttle is still in an area where it can be moved by a leg/foot as described.

@Logarr Ah right, yeah.I have only seen a C42 up close once and I thought I remembered there being one between the 2 seats, not one between the legs of each seat. Thanks for the clarification.

This accident related to the confusing controls of the C42.  https://assets.publishing.service.gov.uk/media/604f43aad3bf7f1d142070af/Ikarus_C42_FB100_Bravo_G-OSPH_04-21.pdf

@Jamiec: I found https://youtu.be/Bc0qLMXmSdM?si=TwSQyxC17esyMy_N&t=79 which is a cockpit tour of a C42.  That point in the video shows how the throttle is linked between sides, between the legs of the two occupants.  Having no prior knowledge of the C42 myself, this wasn't clear from the question.

@AnonymousPhysicist To be fair, one can imagine an analogous mistake in any airplane with a center throttle and left-and-right sticks or yokes, but still, it is a bizarre and apparently dangerous arrangement. Does this airplane require a type certificate or the equivalent in the countries in which it may be operated? (In a quick search, I found a type approval in the UK, which sounds like the equivalent.) If there is an incident reporting system in the country where this happened, I would encourage this question's author to make one.

You did about as well as you could in the circumstances.
People tend to pull their legs back because they're afraid of interfering with the rudder pedals.
In your briefing, you don't want to freak out the passenger but at the same time you want to impress upon them the gravity of that sort of thing. Emphasize the throttle location and make them be conscious of it in a way that keeps them on edge without terrifying them, and keep your hand on your throttle on climbout. Emphasize they can keep their feet forward as long as they don't rest them right on the pedals themselves.
Repetition is one of the keys to learning and internalizing something, so brief it first, then casually mention in a reassuring way a few times before takeoff.
And, as I said, only other thing to do is keep your hand on your throttle until at a safe altitude in case they do it anyway.
I have to say, the throttle placement on the C-42 is absolutely bizarre, one of those "what the heck were they thinking?" moments.  A much better throttle placement with a center stick is the Zenith method of two push/pull throttles, one near the left edge and one near the right edge of the instrument panel, high enough not to get banged by someone's knee when climbing in. If you sit in a Zenith with that arrangement and try it out, you will immediately go "What on earth were they thinking?", regarding the Icarus, yourself.
They probably did it that way to save a few bucks from the cost of two cable assemblies by having one cable down the middle operated by a lever sticking out each side. Where to put the handles? Why not in the worst possible place they can think of?
At minimum, there should be a way to easily remove the right hand throttle for doing passenger rides. I would check if that is possible.

Your commentary made me laugh John, so thank you :)
The throttle stick does (and was) "folded" down, but obviously that didn't stop it being caught. Still, another reason to upgrade to a Eurofox when possible ;)

The other problem with the throttle placement is it makes you look like you're in love with yourself, if you get my drift.... or, you like to do a Michael Jackson crotch grab impersonation while you fly. LOL

Not sure what's allowed in aviation, but could some sheets (or wooden boards) be mounted under the seat to make it impossible to put the legs there?

@Arsenal The manufacturer could make a cover that has a slot with only the knob itself protruding through that would make it more difficult. Probably they aren't getting enough complaints from owners and operators to do anything about it. It wouldn't hurt for Cloud to write to the OEM and complain about the design, just to put it on the record. It'll probably take a crash from that sort of incident for anything to be done about it.

As a non pilot, I still wonder ... should the passenger be instructed to f-bomb or otherwise announce very clearly if they accidentally interfered with anything or think they did?

Aviate, navigate, communicate.
I'm sure in that moment you had some very spicy communication you wanted to make to that passenger.  However, communication is #3 on that list.  Only after the airplane is flying like a proper airplane, and aimed in the right direction, do you deal with the passenger.
However, fair chance the passenger was well aware that an upset just happened, and whose fault it was, and that it nearly killed all of you.   It's possible no additional communication is required.

Aviate, navigate, communicate, slap.


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How do you capture the localizer in an A320?
I understand that pushing 'Approach' should do it (when in range), but it doesn't. There must be another step that I'm missing (the computer has been set up so it's not that).
What is the step-by-step procedure?

On the MCDU F-PLN page, select the arrival airport (LSK6L) and then select ARRIVAL (LSK1R). Then select the ILS approach you intend to fly. Make sure the ILS approach is now shown under APPR, e.g.:

Frequency tuning is automatic, there is no need to manually dial in the localizer frequency or select a course. You can however verify these on the RAD NAV page, e.g.:

Select the LS push button on both EFIS controllers (CPT and F/O) and optionally also on the standby instrument. You should now see ILS indications on the PFD:

Activate the APPR phase on the MCDU. This happens automatically when reaching the deceleration point (circled magenta D on the ND), but you can manually enable it via the MCDU PERF page using "ACTIVATE APPR PHASE" (and confirm):

Enable APPR mode on the FCU:

You can optionally enable the second autopilot at this stage as well. You should see both LOC and G/S in blue (armed) on the FMA now:

Now fly an intercept heading across the localizer. The LOC mode will become active automatically and the aircraft will establish itself on the localizer. Afterwards, the glideslope will be captured automatically (note that the other way round is often disabled by company policy).

All images from: FlyByWire A320 Beginner's Guide

What does the 2nd AP do?

@Cloud If you want to do a Cat II or III autoland, you need both autopilots to be engaged. Even if you don't plan on doing an autoland, it can be helpful to have both engaged during approach because if one fails, you will only down-grade to CAT1 SINGLE instead of a complete autopilot disengagement (which would typically require a go around on final approach).

source: Stack Exchange

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sort: votes


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What is the difference between "Crew weight" and "Occupant Limit"?
On page 11 of the Eurofox POH it states:

Max crew weight per seat......................................................83 kg (Note: occupant limit is 100kgs per seat)

What does this mean? What is the difference between "Crew weight" and "Occupant Limit"?
Perhaps it just means if you weigh 83kg without clothes, first thing in the morning, then after adding clothes, shoes, and your on person equipment, etc. you may be up to 100kg total?

Your link doesn't seem to link to "page 11" but to the main website.

Yea the POH links are at the bottom of that page - they seem to be on a public GDrive @RalphJ

This is basically the difference between "Operational" and "Structural" limits. Quite often regulatory demand is that things like seats, harnesses, etc can withstand a higher load that you would typically expect to find in "normal" usage.
The structural limit of the seat pan appears to be 200Kg from a POH online the wording is very slightly different to the one you quoted, and perhaps gives a bit more context:

Max crew weight per seat 83 kg (Note: occupant limit is 100kgs per seat or 200kgs for the seat pan)

This is accompanied by a warning which seems to backup my assertion that this is a structural rather than operational limitation:

WARNING
Make sure that above mentioned weight limits are strictly followed.
Structural failures which result from overloading of the aircraft may be dramatic and catastrophic.

Further qualification is also included

The additional stress placed on the structural parts by overloading can accelerate the occurrence of metal fatigue failures. Also flight characteristics might change significantly when the aircraft is overloaded. Takeoff and landing distance are significantly longer for overloaded aircraft. Overloading and out of balance loading of the aircraft is one of the most common causes of accidents

What this tells me is that at 83Kg you're well within the limits of the seat pan. Although structurally, you are safe between 83 and 100Kg per seat, you're increasingly stressing the structure to it's limit which if continued over time may result in structural failure. You basically, wouldn't want to be regularly flying round with two 100Kg people or for extended periods of time.

Thanks Jamie, it's a shame they can't be built to be stronger than that

Two 83Kg adults as a fairly decent lifting capacity for such a small aircraft don't you think? I'd be worried about a 100Kg person being able to get in and out a light aircraft easily.

Since they list # of seats as 2, might "crew" be the pilot, front seat, and "occupant" be the other seat?

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What callsigns do UK Medical Emergency Response Teams use?
I'm making a simulation game and there's a large focus on the humanitarian effort military personnel put in, putting aside the shooting and more on the story. Part of this is a Medical Emergency Response Team (MERT) landing with radio communication in the background, which obviously is using callsigns.
For the purpose of realism, I am trying to find references for what callsigns are used for these MERT aircraft/teams. Does anyone have any idea what a MERT team might be called? I'm looking specifically for UK forces however NATO is also fine.

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Why does the UH60 have a titled tail rotor?
I've been looking at helicopter design recently, particularly UK military helicopters. I've noticed that most tail rotors are parallel/flush with the tail of the helicopter in most designs. When looking at the UH-60, I noticed that the tail rotor is diagonal WRT the tail (see image below).
My questions are:

Why is this?
Does this impact it's the ability to counter torque?
Does the rear rotor for the UH-60 have a component of lift?

This seems familiar--??

I did check similar questions when writing the title. If there's already an answer out in the ether, I apologise!

Yep, that does it! Although, from that post alone, I don't see how it can fully counter the torque without having too much rear thrust in the lift component.

@ShaunCockram check the link at the bottom of my answer in Bianfable's linked post.  It's a study of canted rotor effects.


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How many tanks does an A350 have?
How many tanks are there on an A350? Where are they located? Is it a common configuration among large aircraft?

The two configurations of A350 have different capacity.

A350-900: 138,000 liters / 36,456 US gallons
A350-1000: 156,000 liters / 41,212 US gallons

The tanks are shown in this picture:

Source

In addition to Farhan's answer, we can also say that A350-900ULR (Ultra Long Range) version, capable of 20 hours of non-stop flights and up to 9,700 nautical miles, or 1,600 more than the standard A350-900, integrates a modified fuel system, which increases the aircraft’s fuel carrying capacity by 24,000 litres without the need for additional fuel tanks, increasing fuel carrying capacity from 141,000 litres to 165,000 litres.
Benefitting from the A350-900’s unique flexibility, the extended range capability does not involve installation of additional fuel tanks, but rather an adaptation of the fuel system within the existing fuel tank.

So the standard A350-900 has large unusable spaces in its fuel tanks?

Yes, in a some way, it uses additional space already available in the existing tanks and some of the engineering development, involved the relocation of sensors in the fuel system, enabling existing tanks to carry the maximum fuel load for the ULR. In addition, there are some minor aerodinamic improvements and an increased MTOW.

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Does a sudden drop of the velocity of the headwind affect the airspeed by lowering it?
I had a discussion about air speeds with one of my instructors recently. He is claiming that there is a sudden drop in the wind velocity as you get closer to the ground (which is absolutely true, due to the wind friction with the ground). However, he also says that this will affect the airspeed by making it lower and this could be dangerous because it could lead to stall conditions.
For example: he says that, if my approach is with 90km/h airspeed, the headwind is 30km/h at a certain height and by the ground the headwind goes down to 10km/h, and the stall speed is 80 km/h, I will stall because the air speed will drop down to 70km/h.
Here is where I am confused, since I have read before that the wind does not affect the air speed in any way and it will only affect the ground speed by making it 20km/h higher.
Could you please try to make this clear for me?

Welcome to Aviation.SE! Nice first question, clear and concise. Hope to see you more in the future (-;

This is a great question. My question is, how can a pilot compensate for this effect?

in some way you should be aware of the wind speed and direction before the approach. This information you can get from the ATC, or if there is no ATC and you are doing circuits at your home airfield you could estimate the wind speed and direction before the flight. So recently I found a general equation for the airspeed that you need to set during approach:

Approach Airspeed=1,5xStallspeed(1,5 is safety factor)+0,5x headwind velocity. So, you should be prepared for this effect before your approach.If not prepared adding thrust will help. If flying glider(no engines) nose down to gain airspeed.

Your airspeed does not remain constant because of inertia: it takes more time for the airplane to adapt to the new relative wind, compared to the time it takes for the wind to change.
Example One: you're flying 80 knots and the headwind is 20 knots. Over a time of 3 minutes, the headwind gradually reduces from 20 knots to 10 knots. Since the change is gradual, you will notice the ground speed smoothly increases from 60 knots to 70 knots.
Example Two: you're flying 80 knots and the headwind is 20 knots. In 2 seconds, the wind drops from 20 knots to 10 knots. At the start (t = 0), you are moving 60 knots over the ground. However, 2 seconds later, the plane has not yet accelerated 10 knots faster (maybe only 61.5 knots), but the wind is now 10 knots. Therefore you experience an airspeed drop in 2 seconds from 80 knots to 71.5 knots.
Given sufficient altitude, the plane will eventually speed up to 70 knots ground speed (airspeed 80 knots again). When you are landing, you may end up touching down short of the runway if corrective actions are not taken in a timely manner.

The extreme example can sometimes make it plain. Say you are flying at 50 knots with a 50 knot headwind.  What happens if the headwind goes to 0 knots? The airplane has no real velocity, but it will gain velocity quickly in a downward direction. Ground speed is not so important when high, but when low, ground speed becomes very more important.
Common approach formula for gusty conditions:
gust factor / 2  + approach speed = new approach speed
20 gusting to 30, a 10 gust factor,  10/2 = 5, add 5 to your approach speed

You always fly with respect to the mass of air, but when flying in a wind gradient, (as is the case in the example) you can suddenly find yourself with an insufficient headwind, hence not enough lift, and descending rapidly. If you try to compensate by rising the nose, you may stall...

Yes, this is exactly what he told me, but I still don't get why your airspeed will drop down (in wind gradient) instead of remaining constant and making the ground speed higher.

@The Fly  If the mass of the plane were negligible, with zero inertia, it will adapt immediately to any wind gradient-motivated change in the airspeed, but  having a mass, it has an inertia too, making it relatively slow to adapt.

So, as I understand the wind does not change the airspeed only in case when there is no sudden change, so the aircraft could accelerate to its initial airspeed ?

@The Fly  When landing with a headwind having an important gradient, one should pay attention to have enough airspeed (and thus potential reserve lift) to compensate for any sudden, transient change in airspeed.

A lot of answers (all corect) come from a physics/mecanics point of view,so I’ll try to come up with a more-aviation-themed answer: Trim speed
Your airplane is trimmed for a specific speed. With no movement on the control stick the plane is designed to keep whatever airspeed the plot has trimmed for, by pitching up and down.
When your wind changes, or rather when you fly into a different mass of air that moves at a different speed/direction (wich we call wind on the ground), your indicated airspeed will change, and the plane will nicely struggle to regain the originally trimmed speed, yes, by pitching up and down.
Naturally this process takes a few moments, to accelerate/decelerate the ship. The larger the aircraft, the longer it takes. On a large jet it can take 10s of seconds indeed.
In most cases the pilot will usually compensate with thrust to regain the desired speed. Why? Because waiting for the ship to return to trim-speed will take too long and, more importanly, it willalso make the airplane climb/descend , usually messing up your nice 3 degrees approach path on final.

Yes a sudden horizontal wind gust suddenly changes relative air speed.
Adding speeds must be done at any moment in time. One moment you have a headwind, the next moment you don't: that's a drop in air speed. If you don't change the power setting, the aircraft will accelerate until the original airspeed is reached again, but until that time you have lower airspeed.

In the spirit of blake's answer, lets look at a real world case:
You're flying along and your airspeed is getting too high.  You respond by lowering your airspeed to what it's supposed to be.  The wind suddenly reverses, your airspeed is too low.  Delta Airlines flight 191 is splattered across Dallas with 136 dead and the airline industry got a big wake-up call of the dangers of microbursts.

There's more to it than that.  They had an episode where they gained headwind, started to shed airspeed, thought twice about it, had it reverse on them and saw how that could go... experienced some up/downdrafts... and continued the approach nonetheless and got into more of the same. So it's also a lesson of knowing when to quit.

@Harper Yeah, I was only looking at what actually swatted them from the sky, not what lead up to it.

I don’t think this actually answers the question asked and should probably be a comment.

@Notts90 I'm showing that in the real world it does happen, that's showing that the answer to the original question is true.

Absolutely a sudden drop in headwind speed will temporarily lower your airspeed, due to the airplane's inertia, as many answers have noted.  That's why it's wise to carry extra airspeed near the ground in gusty conditions.
Another point not noted in most other answers is that if you in are in a prolonged descent through a CONSTANT wind gradient-- i.e. the rate of decrease in headwind is constant with altitude-- your aircraft will stabilize at the normal trimmed airspeed, but a nose-lower-than-usual pitch attitude, and a higher-than-normal sink rate.  This is another reason why it's wise to carry extra airspeed when landing in strong wind-- if there's a strong gradient, which there often will be, then it takes extra energy (airspeed) to round out from the steeper-than-usual glide path.  (Alternatively, in a powered plane, you could carry some extra power to preserve your normal glide path.)
So, take your pick-- in sunny turbulent conditions, strong winds usually are associated with strong gusts, and in smooth overcast conditions or in stable marine air, strong winds usually cause a pronounced wind gradient.  Either way, you'll likely want to carry some extra airspeed for landing.  There is nearly always SOME amount of wind gradient near the ground and this has a very real effect on the dynamics of flight.

There are two things going on here.
1 - Your speed relative to the ground.
2 - Your lift.
Lets assume you leave your engine rpms the same and the engine puts out the same energy at all times.
1 - speed relative to the ground will increase as your relative speed is your aircraft speed moving forward, minus any head wind. Now a head wind of 20knots wont slow you down exactly 20 knots as there is the matter of wind resistence / aerodyamics of the craft to take into account but in general my above equation is true.
2 - Lift. If there was no head wind, or any wind, then lift is directly controlled by your forward speed and the angle of attack of the wing. if the wing angle stays the same then lift increases as a head wind increases as there is more air flowing backwards over the wing. A tail wind decreases the lift.
Ground speed may decrease as head winds decrease as you may have to lift your nose to increase the angle of attack to maintain lift. if the engine remains the same revs then more energy is spent in an upwards direction and less on a forwards direction.


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What is the name for a flap that increases the wing's area but not its camber?
Flaps are high-lift devices mounted to the rear portion of an aircraft's wing.

Some types of flaps increase lift by increasing the wing's camber, or, at least, that of its lower surface (plain flaps, split flaps, Junkers flaps).
Most flaps increase lift by increasing both the wing's area and its camber (Fowler flaps, gouge flaps, Fairey-Youngman flaps, zap flaps).

What would one call a flap that increased the wing's area, but not its camber (like the first stage of a Fowler flap)?

A flap that is broken.

Useless flap.
It is always the increase in camber that increases the lift. The reason to increase the chord is that if the curvature was increased too much, the flow would separate and the wing would stall, so the flaps move aft to be able to move down more while still maintain moderate curvature.
The Fowler flaps do move a bit down even in the first step, and the slats move forward and down with (or even before) them, so the camber increases even in the first step.

...so how does the increase in wing area avoid increasing lift directly?

@Sean, because lift is not proportional to area. It depends on circulation, the ability of the wing to turn the air flow downward and that depends on the whole profile of the wing. The coefficient of lift is usually given relative to wing area so we can compare efficiency of different wings, but that does not mean it is independent of scale. It isn't. Extending the wing without adding camber will not increase the circulation around it, so it won't increase lift either.


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Do a turboprop’s compressor and turbine rotors windmill when the engine is shut down and feathered?
If a jet engine is shut down in flight, it continues to turn due to the aircraft’s forward motion forcing air through the engine, causing it to “windmill” in the airflow.
Is this also true for turboprops?  When a turboprop engine is shut down and its propeller feathered, do its compressor and turbine rotors keep windmilling in the aircraft’s slipstream, or do turboprops have some way of closing off their engine intakes to prevent this when the engine is shut down?

An interesting fact is, a lot of turboprops are mounted reverse, e.g. exhaust facing front ("front" meaning the side of the output shaft, which is why a lot of turboprops have exhaust port on the front and bottom). This makes windmilling the core quite counter-intuitive (not saying it's impossible).

A feathered propeller is designed not to windmill in flight, however in the case of a power turbine or even a propeller connected to both the compressor and turbine, it's far easier to turn than an old radial when in the feathered position.
Nothing physically stops the propeller from turning when feathered beyond the force required to turn the power turbine/gearing or whatever the propeller is connected to and the air hitting it at the right angle. Straight airflow shouldn't turn it, however any flow from the sides would turn a feathered turboprop. Unlike a turbofan, the propeller changes pitch so the air affects it differently.

There is no any closing. Why do you want to prevent windmilling in a turbo prop? Turbo props are free power turbines. Compressor is not connected with propeller so it can windmill.

Except for the TPE-331 and others.

T56 is single spool


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Why doesn't the Tu-154's center engine have a thrust reverser?
In this gorgeous photo of a landing Tu-154, one can clearly see that the lateral engines are equipped with thrust reversers, but the center engine is not.
Why?

This aircraft is not the only one with only part of its engine fitted with reverses. See Why doesn't the A380 use its outboard thrust reversers?

Note that on the other hand, the falcon 7X seems to have a reverse on its center engine but I fail to see reverse deployment on the 2 other engines on landing videos

@ManuH: The Yak-40 is another trijet with a reverser on the center engine but not the side ones.

Several I guess:

There is no way to store them on the middle one in a way not increasing drag during flight.
In any possible configuration they would blow hot exhaust always against some body part, thus making it rather inefficient.

But maybe most important:

Two reversed engines already produce more than enough breaking power, no need to spend money on another. In fact, even one would be good for all purpose, but asymmetric force isn't a good idea either :))

In contradiction to your first two points, the 727 (the Tu-154's U.S. equivalent) does have a reverser on the center engine.

Just because another similar model didn't face a design challenge doesn't mean the Tu-154 didn't face said issue.

It wouldn't be logical, as clamshell reversers wouldn't fit very well, and bucket reversers would require a modified fuselage. Plus they'd add extra weight. That's why almost no fighter aircraft with one engine has thrust reversers. (Although the Northrop F-20 Tigershark could be modified to have a thrust reverser, and there was a North American F-100 Super Sabre which was retrofitted with a functional thrust reverser. If you want to learn more about it, search for the NF-100F. There were 3, but only 1 had a Rohr thrust reverser.)


text:
Why didn’t the 757 have manual-reversion capability?
The Boeing 757 was the highest-capacity and latest-designed narrowbody Boeing ever produced (and, in the case of the 757-300, the highest-capacity narrowbody anyone ever produced); it was also the only Boeing narrowbody lacking any form of manual-reversion capability for its flight controls in the event of a total hydraulic failure.
Now, I can sort of see why Boeing didn’t bother to give their widebodies manual-reversion capability (even if I don’t agree with their reasoning on that point), but the 757 is just a large narrowbody, and not even Boeing's largest; the 707 was even heavier (123,830 kg MTOW for the 757-300, versus 151,500 kg for the 707-320B/C), and it had full manual backups for its flight controls.  Also, in the time since they decided to leave manual reversion out of the 757, they’ve grown the 737 to near-757 size, and yet haven’t had any trouble at all keeping its manual-reversion system working!
Besides, if our friends beyond the Iron Curtain could do it all the way back in the 1960s (MTOW 165,000 kg)...
The only reason I can see that would sort of make even a bit of sense (if you scrunch up your eyes and look at it in a certain very-specific sort of way) would be if they left it out in order to avoid introducing excessive differences between the piloting skills required for the 757 and those required for the (widebody, and, thus, reversion-free) 767, and thereby possibly jeopardising the common type rating pilots can obtain for the two - but how can operational convenience possibly justify skimping on safety?
Why did Boeing leave manual-reversion capability out of the 757?

I'm no expert, so I'll only post this as a comment, but two possible reasons I can imagine: (1) the 737 (introduced in 1967) was the last design from Boeing to have manual reversion, for later aircraft (such as the 757, which came 15 years later) they probably considered hydraulics reliable enough to allow removing this feature. (2) the desire to have a common type certificate with the 767 may have also played a part

When you have controls designed to be operated manually, in an airplane that heavy and that fast, you have to include things to provide aerodynamic force compensation like servo tabs and offset hinge lines (look at the IL-82's rudder hinges; like a B-29's...the most obvious tell-tail of manual controls on a large aircraft) to make the control forces reasonably manageable, and even there, I can say with pretty much total certainty the IL-82 required muscles the size of fence posts to operate comfortably.  A jet like that with B-29 flight controls is hardly a leap forward.  You also have to mass balance the surfaces because there are is no flutter damping capability afforded by the mechanical control linkages.  All rather heavy.
When you have hydraulic controls, you can get away without mass balancing the surfaces, without servo tabs, and without offset hinges, because the hydraulic actuators (plus flutter dampers in some cases) provide all the required force, AND the required flutter resistance.
So, if you are going to design a hydraulically boosted system with manual reversion, you have to incorporate some of those aerodynamic force aids to be able to operate the controls manually.  But once you have a design that is sufficiently robust from a design/risk/failure tolerance perspective to operate with hydraulics only, there is no point in including manual reversion.  It's a step backwards, adding all kinds of complexity and weight for no benefit.


text:
What is this noise?
In this video of a C42 landing, there is an audible, intermittent buzzing noise that persists until landing, at the 59 second mark, it reaches its loudest peak.
What is the noise? It's not a stall horn, as the C42 doesn't have one. It sounds electrical, but I'm not sure. I have noticed this on most C42s I have flown, so this is not particular to this video or aircraft.

Barely audible IMO, is it something you were worried about at the time? To me it sounds like the usual sort of sound of a metal airframe flexing/vibrating slightly in gusty conditions.

I'd say not audible over engine and other noise. Whatever it is I don't think an audio recording is going to id it.

It's nothing mechanical other than possibly a loose fairing. Not falling off loose, but loose enough to vibrate in the air stream.
It sounds a little bit like the reed type stall horn used on Cessnas. They have a hole in the leading edge, and above a certain angle of attack, the air blast entering the hole activates the reed in the duct leading into the cockpit, with a similar, but much louder sound, a bit like the little horn on a scooter. So it's not from that.
The most likely source is a piece of plastic or sheet metal, with a gap between an edge and a surface, creating the same sort of effect as air blows into or around it when AOA or yaw angle is just so. Probably, somewhere in the fairing materials around the windshield, wing roots or doors, a small hole or gap is causing some piece of plastic or aluminum to resonate at that frequency and make the sound.
Check for loose fairings/fairing strips.  If nothing is amiss, not much to do unless it really bothered you and you owned the plane. In that case, if I was trying to eliminate it, I'd be looking for gaps in fairings etc, exposed flexible edges, and taping them over and trying out the result.

It's very hard to tell the source of a sound from a video alone, it's hard enough at the time when you can at least perceive where about a sound is coming from.
I could make some wild guesses, as with anything like this if it concerns you get a qualified engineer to check it over.

Metal airframes have some "play" and you often, especially in gusty conditions, get some vibration in the plates. A slightly lose rivet will allow some vibration between parts sometimes heard as a whistling or buzzing sound

Engines are held in place by multiple bolts, if one is slightly lose or missing, the engine may vibrate because of the spinning of the prop. get all the engine mounts checked or eyeball them yourself. It's a useful skill to be able to identify all the engine mounts - I'd want to check them before every flight if possible.... not always easy with some cowlings.

Baggage. Could there have been two containers in any baggage area touching and causing a buzzing sound due to vibration? This is probably the most likely candidate if I'm honest!

Lastly, check your prop, even a decent size notch gouged out can unbalance it and cause extra vibration leading to one or more of the above.

Many thanks for the answer, I guess as you say, it's very hard to identify from a video but these are good pointers :)

@Cloud was that your first visit to Sandown? Great airfield. Did you meet Dan the owner - proper character!

Second visit, loved the views! Yes I did! He asked me if I wanted a T-Shirt that said 'triple Cs' on it as I flew from Clench Common... I asked what that meant and he said "Clench Common..." well, I won't include the last word :D


text:
Is a 3 seat Microlight build possible?
Many Microlights have weights of no more than 450kg, as that was the old weight limit. Now that the limit is 650kg, it seems to me that would be enough weight to add an extra seat (80kg for the passenger and 120kg for the added seat and fuselage weight).
Is there any reason this can't be done? If not, are there custom manufacturers that would facilitate this?

Considering your last couple of questions have been followed with a youtube notification on my phone, I'm fully expecting a YT vid of you now with a garden chair strapped into the back of that C42 :D

@Jamiec haha :D Not a bad idea ;)

TL;DR NO
From the British Microlight Aircraft Association web site:

CURRENT UK DEFINITION/S
19th August 2021 - Air Navigation Order Update (600kg - LIGHT SPORT MICROLIGHTS)
A UK Microlight Aeroplane is one designed to carry not more than two persons which has a Maximum Total Weight Authorised (MTWA) not exceeding:

600 kg for a single seat and two seat landplane (Permit to Fly).
650 kg for a single seat and two seat amphibian or floatplane (Permit to Fly).
Stalling speed at the maximum weight authorised not exceeding 45 knots (Calibrated Airspeed).

In other words, the legal definition includes "two seats". The increase 650 kg for an amphibian or floatplane (was 495 kg) or 600 kg for a landplane (was 450 kg) doesn't change the maximum seating capacity.


text:
Can I identify as a student pilot when I'm not?
A few months ago, my original flying instructor took me to a busy airport (Gloucester) as I wasn't comfortable going there by myself for the first time as a low-hours pilot who only really uses grass strips.
Anyway, the most difficult part for me, was the radio, readbacks and pattern / queuing procedures.
Could I (dishonestly) identify myself as a student pilot if I go again by myself, so that ATC will speak slower and be more helpful? Or would that be breaking any regulations?

How about identifying as a "low hours pilot"?

Suggestion: change title to "Can I identify myself to ATC as...".   In general, in this day and age, anytime someone starts talking about how they "identify", the reader's mind goes to all kinds of places that you probably didn't intend.  Personally, I identify as a World War One ace, much like Snoopy did.

PS-- duplicate or near-duplicate of https://aviation.stackexchange.com/questions/287/can-you-tell-atc-you-are-a-student-pilot-when-you-are-not?rq=1

@quietflyer weird this didn't come up when I reviewed the post.... thanks :)


text:
How much wind will rip an aircraft apart?
I would like to know how to calculate how much wind would be required to rip any particular aircraft type apart.
In the case of N3079M, (video breakdown here), it took some severe storms (estimated 40 - 50 knots) to break apart a Piper PA-28-161 Warrior II.
How can you calculate, for any particular type, what wind speed will do this?
Note - I do not believe the "maximum crosswind component" in the POH covers this, as this is for landing mostly and I know from experience that speed is way under that which the aircraft can handle structurally.

You're thinking about it the wrong way. It's not "winds ripping the airplane apart" literally. It's gusts, or accelerations induced by pilot control input, that exceeded the airplane's G limits. Hoover is using a kind of short hand to describe the effects of flying into violent turbulence from a thunderstorm cell and losing control and overstressing the airframe. The phrasing he uses make it sound like the airplane was minding its own business and suddenly some force suddenly tore it to shreds. That's not what happened.
Theoretically, if you are below maneuvering speed, Va, in a light plane, stalling angle of attack will be exceeded before gusts can exceed the G limits of the airframe. If you've been trained properly and are about to enter really rough air, you make sure you are below Va. On light aircraft, Va applies to control inputs, not gust loads, but it's assumed to be about the same.
Transport aircraft have an additional limit called Turbulent Air Penetration Speed, below which you are protected from gust overloads by the wing's stalling AOA, independent of control inputs. This is because once the airplane gets really big, inertial effects mean the speed at which control deflections can exceed G load, and the speed at which gust loads can exceed G load, can differ quite a lot. On a transport the TAPS is usually significantly lower than Va, and is the value you observe when flying into turbulence.
Anyway, the issue isn't working out how strong violent gusts have to be to be safe from "being ripped apart". This airplane was likely broken up because they lost control in extreme turbulence, at night, and likely eventually had the speed well above Va, while still in the violent turbulence. They likely came out of it near vertical in a spiral dive, and the first thing to come off is the tail or part of the tail (ADS-B doesn't tell you what the airplane's actual airspeed was, only its groundspeed).
The moral of this story isn't about flying in rough air in itself. It's staying far away from thunderstorms, period. In the daytime you stay far away from cells. With jets with on board weather radar, you are trained to give cells at least a 20 mile berth, on the upwind side if at all possible (to avoid hail).
Flying at night, VFR, with cells in the vicinity or heading their way, without live weather radar on board, was suicidal idiocy. The "TSRAs" in the TAF, at night, would keep any lightplane pilot with half a brain on the ground. Another thing is the painted areas on weather radar (which can have a lag of several minutes if you're using a display routed through the internet and thus have a large position error) only tell you where there's water not turbulence.
If you avoid thunderstorms, it's just about impossible to get caught in this kind of situation outside of phenomena like rotors below ridge lines, or wake turbulence from a much larger airplane. So forget about calculating wind turbulence or speed limits. The exact numbers will be unknown; just stay far away from thunderstorms, and don't go on cross country flights VFR if there's a risk of getting anywhere near them.

I beg to differ somewhat, but enjoyed reading your answer.

Differ away. I'm interested.

Done for your review.

That's basically a supplement to my post introducing new information. Good job.

One would agree that excessive G loading, positive or negative, is the prime suspect to aircraft destruction in turbulence, but one cannot rule out stress  on the vertical stabilizer from cross wind gusts.
Although it has been pointed out it is a great idea to slow down to or below the aircraft Abrupt manuvering speed in turbulence, it is not only pilot control inputs that will destroy an aircraft in a severe thundestorm.
Aircraft are advised to stay away from thunderstorms because:
1. Strong localized updrafts, downdrafts, and circular winds are common
2.  Thunderstorms can develop and intensify in a matter of minutes
3.  Radar information may not be in real time, and
information even 15 minutes old may be dangerously inaccurate
4.  Thunderstorms commonly move at over 30 miles per hour, and can move as fast as 70 miles per hour
This means the radar may have shown the storms that did in N3079M up to 15 miles from where they actually were.  It is quite possible the aircraft flew directly into one.
In conditions of turbulence, the aircraft's own mass (inertia) is its worst enemy.  A balsa model can withstand a strong gust because it is very light, but a full scale aircraft will experience gust loads until it has time to accelerate sufficiently to reduce the load and then ...

another gust from a different direction

One can see why flying from a 60 mph updraft into a 60 mph down draft will buckle an aircraft.  Negative G load limits are usually less than positive ones.
The actually calculations could be modeled as a gust force (or a control input force) per area vs the aircraft component area rated strength.  Distributing mass across the wing will do much to improve its survivability in turbulence$^1$.
Sample Calculation:
Wind Pressure (lbs/ft$^2$) = 0.00256 × V$^2$ mph
Wing area PA 28-161: 170 ft$^2$
60 mph updraft:  0.00256 × 60$^2$ = 9.2 lbs/ft$^2$
Load on Wing:  9.2 × 170 = 1564 lbs
120 mph wind shear (into downdraft):  0.00256 × 120$^2$ = 36.9 lbs/ft$^2$
Load on Wing: 36.9 × 170 = 6373 lbs
Weight Piper 28-161 Cadet:   2325 lbs
Negative G load from downdraft (windshear) = 6373/2325 = -2.74 G
G load limits: + 3.8, - 1.5
So, one might have a combination of shear and control input quickly overloading the wing, as well.
$^1$ the P3 Orion "Hurricane hunter" aircraft serve well in this role.


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What are the survival rates from different altitudes?
In this video of someone making a homemade electric aircraft, at around 19:44 into the video, the creator shows his estimates of survival chances if he stalled and crashed from various altitudes, a screen grab is below.

Is this accurate, broadly speaking? 5% from 200ft seems very low to me, I thought it'd be more like 50% at least.
By the way, the reason he enters 100% over 1000ft is on the assumption a parachute is installed. Now, I would personally never put 100% probability to... well, anything.

This kid looks super smart, and an amazing job doing what he clearly loves. But I really wouldn't put much stock into a back-of-the-envelope guestimate of his survivability. You fall from 49ft in that, you're just as dead as 51ft.

@Jamiec you think a 49ft fall would kill you?

Thats roughly the 4th floor of a building, would you fancy your chances jumping from there? It's going to hurt, a lot, if not kill you.  Now wrap yourself in wood/metal/electric motors and go again.

Also, your question you say "5% from 200ft seems very low to me, I thought it'd be more like 50% at least." - Would you jump from the 25th floor of a building and really expect to live 50% of the time? I think you're underestimating just how high 200ft is!

This really, really seem like a problem crying out for Bayesian

Great video and outstanding build.  It seemed his point (compared to the 80 knot plane) was being very low and slow (25 knots) gave more chances of survival nearer the ground.  1000 feet may have been his estimate of minimum survival altitude with parachute deployment (time) for both aircraft.

So much depends on the airframe how hard it hits the ground, the type and extent of structure and mass between you and the surface, and the kind of restraints you are wearing. Peter's talking about the thing coming apart and the survivability of a free fall drop from a vertical distance. We really don't take that into account because the event is so rare. In the real world, the main concern is survivability following a stall spin close to the ground, or a forced landing into a confined space that forces you to crash into objects while still moving.
So much depends on the airplanes. I tow gliders in a Piper Pawnee ag plane (with the hopper tank removed).The Pawnee has the cockpit quite a ways aft, so most of the mass is ahead of you, with a steel tube fuselage that's rather tank-like. There are stories of Pawnees stalling and spinning into the ground and the pilot, strapped tightly into a 4 point harness and a cockpit that remains pretty much fully intact even at that level of impact, walking, or at least limping, away.
At a glider club I was in there was a kid landing a Schweitzer 1-26 that entered a stall spin on a very low turn to final. Only going 30 mph, and starting the spin from maybe 30 ft in the air, the thing more or less hit the ground nose down with a bonk, and he climbed out with nothing more than a sore back.
Shoulder harnesses are critically important. People who don't wear them in crashes often die from head injuries in otherwise perfectly survivable crashes.
If you hit the ground at a decently low speed and the structure between the seat back and your feet remains intact, and you're wearing a shoulder harness, you will probably live, and very well may get away with only leg injuries from the front part of the cockpit folding up.
Ultralights are like the 1-26, and a lot of accidents are survivable just because the energy is so low at impact and as long as you keep your head and torso out of the instrument panel with shoulder restraints, you'll likely live.
Hit the ground while spinning in something faster and heavier, if it's been able to fully develop, and unless you're in a flying tank like a Pawnee, you're probably going to get hurt pretty bad, and maybe killed.  But in accident studies, the number one factor that stands out on surviving or not, is whether or not you're wearing a shoulder harness. the vast majority of ground contacts, while the airplane is under control at the time, while wearing a shoulder harness, are survivable.
Hence the advice to strap in tight and fly it all the way into the crash.

Altitude is not a measurement in "survivability", and I don't think that the guy on the linked video was actually trying to say it was, in the general sense at least.
What he was saying, if I understood correctly, was that at low level he might be OK, but unless he got high enough to deploy a hand operated parachute, that he was toast. So it was stay low or climb quickly though a zone which would not afford him time to deploy his parachute.
Surviving a crash is more about your position, your restraints, and limiting deceleration forces. If you would like a long read on human crash survivability then NATO Science and Technology Organization have produced a paper on Human Tolerance and Crash Survivability.

"...limiting deceleration forces." As the old saying goes, it's not the fall that kills you, it's the sudden stop at the end.

For a more thorough paper on crash survivability I recommend the "Aircraft Crash Survival Design Guide" (link), of which the linked report is just a small excerpt.

His reasoning is that his 30 mph ultralight flies so slowly that his forward speed will be survivable if not much of a vertical speed is added. Then he compares this to a composite 80 mph design where forward speed alone is already enough to possibly get killed in a crash even with the fuselage around you and wearing a restraint.
And that is about right.
However, altitude is a poor metric for survivability. A better is the ISS (injury severity score) which is a numerical score which is derived from an individual's three most severely injured body regions. Many high-velocity impacts resulted in low injury- severity scores, and many low-velocity impacts had high degrees of injury severity (see plot below).
For survival, body posture and the energy absorption capabilities of the ground must be taken into account.

Plot of ISS of falls over estimated impact velocity. Impact velocity was calculated form the height of the fall. Source: Figure 9 from "Study of Impact Tolerance Through Free-Fall Investigations", Highway Safety Research Institute, The University of Michigan, Ann Arbor, Michigan.
Another measure of injury severity is OAIS (Overall Abbreviated Injury Scale). The OAIS is based on the Abbreviated Injury Scale (AIS) which is in use internationally as a method of quantifying injury severity in auto accidents. Plotting this measure over impact velocity (see below, from the same source), there is a good correlation for head impacts age 10 and older and a weak correlation for impacts other than to the head, age 10 and older. No other correlations are evident for impact velocity as an indicator of injury.

Again, from Study of Impact Tolerance Through Free-Fall Investigations:

If the potential indicators selected were good indicators, one would expect to see a positive relationship between the independent and dependent variables — for example, an increase in impact velocity resulting in an increased indication of injury. There is no such indication in the majority of the plots.

Given that Peter Sripol flies over fields and meadows (as opposed to concrete surfaces), his reasoning is correct. But still, it will hurt, even if he crashes from 10 ft of altitude. And his expectation of the plane coming apart is not unreasonable, too, when we consider that he did his load test first and then added more wingspan.

Fig. 10a may support your point better than fig. 9 because it uses OAIS not ISS, and includes points for which OAIS=6, i.e., fatalities.  If fig. 9 plots only survived falls, then it doesn't directly address survivability.

@CamilleGoudeseune Thank you, I will revise the answer tonight. I only wanted to make the point that fall height doesn't determine severity of injury or survivability. The last half of the linked document contains some grim examples ...

@CamilleGoudeseune Oops - some ISS scores are also fatal. In the examples there are two fatal cases with OAIS 5 and ISS 26 only, another with even ISS 16. Text corrected.


text:
Is there anything important to know about flying at ~9000ft for the first time?
When I did my NPPL training, there was a module on flying at minimum altitude, but nothing around high altitude flying, in fact, I've never flown over 3,500ft.
This weekend, I intend to fly up to around 9,000ft just for fun. Obviously I'll do this in an area that doesn't infringe any airspace, i.e. class G airspace.
Is there anything important to know before doing this?

Anything below you will look much smaller when flying at 9k compared to 3.5k.

Don't forget to adjust your mixture control at higher altitudes, you'll need to thin it.

@GdD I don't have one :0

Oh, you have a Rotax, right @Cloud? One less thing to worry about.

@GdD Yep! :) :)

@quietflyer in answer to one of your questions we don't have much class E airspace in the UK. Most (if not all) is in Scotland. Outside for the TMA-like areas of the south east and the more built up areas around other cities plus the corridors between them, it's mostly class G all the way up to FL180

There's really not that much difference between flying at 3,500ft and 9,000ft, however yes there are a few things you should be aware of. The most important, as usual when operating an aircraft, is check your POH. That is your definitive guide to some of the things you'll want to know. There are also some human factors to be aware of.

Service Ceiling: Check the POH for the service ceiling for the aircraft to ensure it is certified for flight at the altitude you expect. From previous questions I'm aware you fly what we call microlights in the UK (ultralights in the US and possibly elsewhere). A quick look for an example POH shows the EuroFOX has a service ceiling of 14,500ft.

Operating environment: Again the POH might establish an ambient temperature range that the aircraft can operate in. The above-linked POH specifies an ambient temperature above -10°C. Keeping in mind that you lose roughly 1.5°C per 1000ft, what temperature on the ground would take you beyond that limit at 9,000ft?

Engine management: If the aircraft you fly has a manual mixture control, then you will want to lean the mixture when cruising at altitude. As the air becomes less dense there is less oxygen available for combustion, so you will not be able to burn all of the fuel at a rich mixture. More information here: Why do we lean the mixture when the air become less dense?

Human factors: Hypoxia is the medical term for when the body is deprived of oxygen. One way this can occur is the lower pressure of oxygen at altitude. Typically people begin to start talking about those effects above about 10,000ft, but it's not like there's some invisible line where below it you're safe and above it you're not. One of the major problems with hypoxia and aviation is that often by the time you're compromised it's too late. So you need to be hyper-aware of the symptoms, and if you have any reservations then carry supplemental oxygen (or just don't push your limits in the first place!). If you're a heavy smoker or asthmatic then you might be more susceptible so speak to an AME if you're concerned.

Something to consider outside of your question. Most people think of height as danger. The higher you are off the ground the more dangerous whatever you're doing is. Notwithstanding the above answer, in an aircraft, altitude equals safety. The higher you are, the further you can go if the engine quits, and the longer time you have to deal with the problem. In a typical light aircraft a rule of thumb is roughly 1.5nm per 1,000ft glide range. So from 3,500ft you might be able to glide 5nm. From 9,000ft that is 13nm. In time, it's the difference between having 4 minutes to deal with the problem before your wheels are on the ground and having 11 minutes. That's a lifetime in an emergency situation!

Comments have been moved to chat; please do not continue the discussion here. Before posting a comment below this one, please review the purposes of comments. Comments that do not request clarification or suggest improvements usually belong as an answer, on [meta], or in [chat]. Comments continuing discussion may be removed.

The main thing you will notice is, if the propeller is fixed pitch, you will have the throttle all the way in to maintain cruise power (9000 ft will limit you to about 65% and the engine will be wound up close to, or at the engine RPM redline, and throttle setting might be limited by redline if the prop is pitched too fine.
The other one is it will be cold and the heater had better be working.
Indicated speeds you use are unchanged, but just be aware that the difference between indicated and true are starting to become significant and your indicated cruising speed will be lower than what you are used to, with less margin between operating speeds and stall (whose indicated airspeed remains the same).
Biggest one is to be aware that your overall energy margin that you get from excess power is declining off to zero as you approach the airplane's service ceiling. If the service ceiling is 12 or 14000 ft, you should still have some energy margin at 9000 ft, but nothing like down low. This applies to maneuvering margins as well; it's easier to stall the thing in a steep turn say.
If you don't have altitude compensating carbs, mixture leaning is an obvious one, but that really applies to all altitudes as soon as you reduce power after takeoff (a full rich mixture is strictly for cylinder cooling at full power, at lower altitudes where full power or close to it is available).
Otherwise, not such a big deal. Don't over-think it. Just learn the facts and keep them in mind.

Yeah in reference to cold, worst pins-and-needles pains I've ever experienced in fingers were upon descending from maybe 16,000 MSL down to ground level at 4000 MSL on a day when temp was up near 90F on the ground  --- ouch ouch ouch !  (No enclosed cockpit on that flight though, actually no fuselage at all.)

That was a hang glider?

Actually yes John...

Love to do that, but I can't run due to plantar fasciitis.

The only thing I'd add is that you'll need to progressively lean the engine as you climb. Watch your EGTs. And don't forget to richen it as you descend.

The plane he flies has Bing carbs which are altitude compensating, and if he has a mixture, I'd assume he's leaning all the time anyway. I lean as soon as I reduce power to climb.

@Gerry's point could apply to other readers with the same question but a different plane.  It's not a bad idea to include something for the benefit of future readers who find this via google, or so later similar questions can get closed as a duplicate of this.


text:
Why do the engineers need to be on board during testing?
I just finished watching National Geographic's Megafactories: Boeing 747-8.
During the test flights, a bunch of engineers are on board the plane, presumably controlling the water tanks that distribute weight, and collecting the data.
Another time I'd seen it was when they were testing detection systems for microbursts. There were about a dozen engineers sitting on the plane, watching monitors while the crew deliberately flew into hazardous conditions.
Why do they risk the safety of these engineers, when presumably the work they're doing could be automated or controlled remotely? For data to be observed, couldn't they do that from the ground?
Is this a case of "we've always done it this way?" Even now that we probably have the technology that would allow the engineers to avoid having to go on test flights, I'm guessing that changing this procedure would be a lengthy and difficult process.
Besides the pilots, why does anyone else need to be on board?

:) If I'm not mistaken, in the past the "engineers" would be the first to cross the bridge they've just built :D

Skin in the game -> better aircraft design.

If I am a pilot and the engineers are doing water-tank CG stress tests, I kind of want them to be on board in case anything happens. And to not do anything that is all that dangerous.

More and more data is collected in flight testing of aircraft. While 50 years ago they might have only designed for a small number of scenarios, the advances in computing allow them to design modern aircraft for thousands of scenarios. Modern certification standards include more and more requirements, which include flight testing for many of these requirements.
While some information is sent to the ground (like in this video), other information may not be. Airplanes in flight test have sensors for temperature, pressure, stress, and many other parameters located throughout the plane. These generate a lot of data, more than may be practical to send on a live data link. There may be several reasons that the engineers would want to analyze a lot of information onboard.
Some of the tests need to have multiple parameters coordinated with the pilots. If they are flight testing stall, for instance, they need to be sure they have flight parameters are correct for that test. The engineers give the pilots guidance on getting the airplane into the right configuration. The engineers also verify that the the information they collect is sufficient for the needs of the test. It's much more expensive to come back and realize they didn't get what they needed and must go back up to re-run the test.
Some of the data is also critical for safety. One subject of the tests is flutter. Flutter conditions can be very dangerous to the aircraft. The engineers help monitor the data and make sure that things don't get out of hand. If a data link were to be interrupted in a case like this, safety could be compromised.

In a perfect world, you wouldn't need the pilots as well...
To your question:

No modern instrument can currently match the feeling of "just being there".
Data recorded on the plane and transmitted to the tower is lagging or even impossible to collect live (due to technical difficulties).
Flying takes a lot of attention from the pilot. Even if they're good engineers (besides being a pilot), you wouldn't want to waste an experiment.
Engineers don't go to preliminary (dangerous) flight test.
Some engineers enjoy being on board the machine they designed.

how much is the realtime delay in data collection?

Commonly, a few (<5) seconds are accumulated.

I would also question the implications of answer 4. By making that statement, you are implying that the flights engineers do go on are not dangerous. If they are moving large quantities of water weight on board, affecting the CG, and recording the effects of the changed CG, it seems that that flight may be (just as) dangerous. Also asnwer 1 is subjective, and an engineer aboard is not likely there for subjective 'feelings'.

I would also question answer 5. IMO, the subjective enjoyment of flying would not be an acceptable reason to risk an engineer's (not REQUIRED for the operation of the plane in flight) life when the mission of the flight is the objective collection of data.

this is a bit off-topic, but engineers who participate in policy-making in their organization, are expected to be biased towards requiring engineers on board.

@Sparkler that's another unsubstantiated claim.

I'd also add that they are there just in case there is something wrong with the equipment or software and the data isn't being recorded correctly.  It would be bad to waste an entire (very expensive) flight because data wasn't being recorded correctly, especially if it could have been fixed without cancelling the flight.

I still want pilots in my perfect world.

@Federico As an engineer (and a pilot) myself, I would probably personally have that bias. :) That being said, part of the reason for that 'bias' is that it's a lot easier to track down problems when you're sitting in front of a system while the problem is occurring than when you're trying to analyze log data and descriptions from people who are not engineers after the fact.

Usually, engineers on board on the aircraft serve the same purpose as engineers in a control room. (The control room for space missions in Houston is probably the best, most widely known example of a control room.)
Having the engineers on board reduces the need to send the data to the ground via telemetry (TM), which may be a necessity based on limited bandwith, etc.  A description and illustration of the control room and its purpose appear here.
It also allows for better coordination amongst the crew, as the pilots, who need information that the engineers are monitoring, can discuss more effectively with the engineers when they are on intercom.
Flight Test Enginners (FTEs) are another kind of engineer on board the aircraft, and they specialize in test conduct. They are present to guide the test pilot, assist in determining if the maneuver was flown correctly, evaluate data quality, and make decisions about whether to continue testing.

Hi Mark. Just a heads up, here: I see you have linked a fair bit to multiplyleadership.com in your answers. While links to external resources to add to your answers (as opposed to the link being the primary content in the answer) can absolutely be beneficial, you should take care to ensure that this is not construed as spamming. See How to not be a spammer in the [help] for further discussion on this.


text:
Could a plane catch up with a skydiver with a failed parachute?
Picture this scenario:
A drop-plane drops off a group of skydivers. One of them pulls his chute and it fails, he pulls his reserve and nothing happens. The skydiver radios the plane to tell the pilot of his predicament. The jumper maximizes drag by spreading his arms and legs wide, the pilot pitches down 40 degrees and redlines the ASI to get parallel to the skydiver, who then flies safely back into the plane.
Is this possible?

It's been done (although as a stunt, not as an emergency recovery): https://www.youtube.com/watch?v=YL9sNrOlK-I

@KennSebesta Great link! The reverse thrust of the Pilatus Porter made this possible. I doubt a regular drop plane could do this.

There was an Imax movie called "Flyers" that featured exactly this maneuver.  It's been many years ago, don't know if you will have much luck googling it.  And of course I can't speak to how closely what was shown on the screen matched to the actual reality of what was going on in real life during the filming -- i.e. whether the stunt was actually performed in real life, or not--

Re "It's been done (although as a stunt, not as an emergency recovery):" -- considering that this was done in the context of wingsuit flying off of terrain, not an actual skydive from a plane-- that seems extremely dumb.  Can you say " compounding the risks as much as possible"?

@quietflyer There's a nice valley at 1:44 in the video, if the entry was unsuccessful, I would assume they'd perform a landing there. Further, as normal for wingsuits, the flyers have parachutes, so a safe landing can be made over many types of terrain in minimal space. Flying an unpowered glider over the same terrain would seem to be a greater hazard.

If the plane was highly modified, was in a dive when the jumpers exited, and everyone had a pretty good idea of what they were doing, maybe...
Red Bull sort of attempted this with their plane swap stunt which ended badly for one of the planes. Keep in mind these planes were equipped with dive brakes to make this stunt possible and were able to dive un-assisted with custom auto pilots (although in your case there is presumably a pilot flying it down). Its also worth mentioning this may have license implications.
Catching up to the sky diver in a maneuverable, stable, way is going to be a tall order if your in an unmodified plane.
Again, Red Bull proved you can indeed base jump into a plane which is also a similar situation and perhaps if the sky divers were wearing a similar suit they could pull it off.

I see no fundamental reason why the plane needs to be "highly modified" or "in a dive". If it has a door big enough to get out of, then its big enough to get back in to. Having enough time/space/power/speed-brakes to be able to match speed is the most critical (and unlikely) bit.

As a choreographed stunt, it would be very difficult and dangerous, but might be possible. The drop plane would need to be in a nearly-vertical dive, since a skydiver in free fall is falling nearly vertically, at a rate of about 10000 feet per minute. Most planes can't dive like this- either they are moving too much horizontally (which will kill the skydivers) or they are essentially falling at their terminal velocity (which is, for most planes, much faster than the skydivers and also Vne).
As a practical matter, it's definitely impossible, and it would be incredibly reckless for a pilot to try. Skydivers don't usually pull their chutes immediately after exit and drop planes don't usually dive at Vne just in case one of the chutes fails. In other words, the skydiver is probably closer to the ground than to the plane by the time they discover their chute isn't working.
Even if the diver immediately radioed the plane and the plane immediately started a max-performance dive at Vne before deploying their magic dive brakes that let it match speed with a skydiver, there simply isn't time for the drop plane to intercept the diver and then recover while the altimeter is still reading a positive number.
To put some numbers on it, suppose a PC-6 drops a diver off at 10000 feet. Less than a minute later, the diver tries to pop their chute at 3000 feet, while the PC-6 is passing through 9000 feet. With around a 10000 fpm descent rate, the diver has a little under 20 seconds to be saved. The PC-6 would have to have an average descent rate of 30000 fpm just to hit the ground at the same time as the diver. As 30000 fpm is around twice Vne for a PC-6, that is unlikely to end well.

After all skydivers are divers not airborne soldiers, and they open the chute at the end of the drop, not the beginning. The moment of truth is simply too low to do anything about it.

Mike Patey did a stunt where people in wingsuits grabbed the wings of his plane. That was hard enough requiring significant reverse thrust to achive the required flight path and speed. Someone with nothing at all to arrest their fall would presumablly be even harder.

A plane can dive at a vertical speed (~150 MPH) which exceeds the terminal velocity of a human with a dead parachute (~100 MPH). This means that in principle, a plane can catch up with a falling parachutist. However, whether or not the plane can save the falling parachutist depends on whether or not it is possible to keep him or her away from the propeller!

The gravity force and air drag force reaches equilibrium and the falling speed stabilizes at about 200 km/h at this point. It is too fast to be survivable. It takes only about 12 seconds to reach this speed.
Hitting a horizontally flying aircraft with the same vertical velocity should not make any difference from hitting the ground.

As noted by Kenn Sebesta, this has actually been done as a stunt (James Bond iirc) so no, it clearly isn't impossible!

Still  do not understand how they did. I would leave the answer for now because Youtube video without comments is not the best ever source. If the vertical speed is zero, hitting the plane is the same as hitting the ground. If the vertical speed is close to 200 km/h, what kind of aircraft should it be to have horizontal speed low enough not to kill a human due that component of velocity.

Use a PC-6 with reversible prop. Otherwise, the speed in a dive will quickly become too high for this to work out.


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How to avoid rotors and other dangerous turbulence around mountains?
I would like to try flying around some mountains but have never done so before. I am aware of some things to look out for:

Lenticular clouds (a sign of mountain wave)
Flying on the leeward side of mountains (where the wind is coming back down)
The minimum safe altitude

Are there any other factors to be aware of? What is the best way to ensure you don't hit rotors that throw the aircraft out of control?
FYI an answer like "stay much higher than the mountains" won't help as I want to practice ridge soaring and using thermals for lift.

I suggest that you read "Mountain Flying Bible" by Sparky Imeson.  https://www.mountainflying.com/products/mfbr_info.html   Also, know that he died in an airplane accident in the mountains.

That comment says it all really! For the love of deity, get in a well equipped aircraft with a highly qualified (mountain flying) instructor and don't listen to advice of random people on the internet!

There are quite a few gliding clubs in the UK that are based near to hills so that they can take advantage of the ridge lift (e.g. Chipping, Sutton Bank, Camphill).  You could book a lesson at one of those, you'll spend most of the day waiting for a flight, which is a great oportunity to pick the brains of the hill flyers.

Flying in mountainous terrain in the UK, with the highest peak at about 2000 ft isn't quite like the Alps or the Rockies, but it's still enough to get you into trouble if you're not careful.
The biggest risk is rotor below the lee side of ridge peaks, so never cross over to the downwind side of a ridge without ample altitude above unless the winds are very light. If a lenticular cloud has formed on the lee side of a peak, the rotor is just below it. Hitting that sort of rotor on a windy day will be like a wake turbulence encounter with an airliner.
Other risks:

Below the rotor, downdrafts or downsloping air on the lee side of ridges.
Flying up valleys that are sloping uphill and you can't tell because you don't have a direct horizon reference. Adding to that, blundering into an uphill valley and not leaving room to turn around once you realize you've blundered into an uphill valley.
Winds are everything. Up a valley, down a valley, across a valley. What the wind is doing is probably 80% of risk management. You have to learn to mentally picture what is happening in the different parts of a valley for a particular wind direction, and you have to be able to discern the wind direction.

Read some books on mountain flying.
Also suggest you follow some channels of paraglider pilots in the UK that do cross country in the Scottish Highlands and the Lake District. The paraglider guys are, for obvious reasons (gossamer delicate wings), the most sensitive to the risks by winds and you can learn quite a lot from them. Plus the channels of glider pilots that do ridge soaring.
Get educated, then maybe go out with somebody with experience to show you the ins and outs.

Are you testing the water, seeking deniability? If you want to learn to fly in thermals, try west Texas, or even southern Arizona. Regarding wave soaring and the dangers related to clear-air conditions in the lee of the ridge, here is something to think about as reported in an updated Plane and Pilot article dated February 16, 2016 -

The NTSB says the probable cause of the 2007 crash of adventurer Steve Fossett was an inadvertent encounter with downdrafts above mountainous terrain that exceeded the climb capability of the Bellanca Super Decathlon he was flying. Downdrafts, high-density altitude and mountainous terrain were all contributing factors. None of those factors should be taken for granted by pilots who fly, or have a desire to fly, in mountainous areas. In simple terms, while wind flows smoothly up the windward side of a mountain, and the updrafts can be used to help an aircraft make it over the crest of the terrain, downdrafts on the leeward side can become terrifyingly strong and turbulent. Areas of turbulence and downdrafts can be surrounded by deceptively smooth air. Just because there are no lenticular clouds, rotor clouds or dust storms doesn’t necessarily mean that conditions are benign. Before conducting a flight in or near mountainous terrain, an experienced pilot should carefully evaluate the weather, especially winds aloft, approaching frontal activity and stability information such as the [lift] index. A smart, inexperienced pilot will confer with someone who knows how to evaluate conditions, and also get a checkout with an instructor qualified to teach mountain flying before venturing into unknown territory.

The emphasis, above, is mine.  In concluding an answer to the question on se-aviation, "What prevents a small plane like a Cessna or Piper from flying as high as a jet?" I noted the following incident regarding rotors -

In 1952, Larry Edgar and Harold Klieforth set an altitude record in a two-place Pratt-Read G-1 glider, soaring to 44,255 ft (13.489 km) in a Sierra wave. However, on April 25, 1955, Larry Edgar's Pratt-Read glider was destroyed in the lee of the Sierra by a rotor-cloud at 17,000 ft (5.2 km) as he was investigating the rotor's turbulent structure at the base of a wave. The acceleration he experienced, in excess of -20g, ripped off his helmet, boots, gloves, and oxygen mask. As he drifted downward he could see parts of his glider being carried upward and worried if he pulled his parachute rip-cord, he might be carried upward as well. Fortunately, he was able to make a parachute landing and survived without breaking any bones. The extreme negative acceleration partially damaged his vision. Edgar was the only one in his sailplane when this happened.

One may think that wave soaring is thrilling in the quiet, clear air at 33,000 ft above the Sierras, or central Rockies, or even the Tetons; air so quiet the only sound one can hear is the tapping of the yaw string on the canopy.   But my concluding comment to that answer was the following -
Aviation, although not inherently dangerous, is, to an even greater extent than the sea, terribly unforgiving of any carelessness, incapacity, or neglect.


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First time passenger flight by two pilots?
In this video, the captain proclaims after take-off:

We were nervous about this, but takeoff went smoothly

It was his first passenger flight in the A350, but still... not exactly what I would want to hear as a passenger. This got me thinking, does it ever happen that two pilots take their first passenger flight on a given type together, or will it always be the case that if it's someones first time, the other pilot will have X amount of hours on that type?

Well, if I were to find I was sitting as a passenger on a flight that was a "first" for, say, the whole crew, I'd rather they be nervous than "HAH, piece of cake, we got this, noooo probleeemz"...

Not only custom and practice but both local and international law forbid that.
I'm sorry I can't cite them and it was your job to look them up before Asking on SE…
Ask any airline for written confirmation that what you speculate on would be contrary not only to internal procedures but also to both local and international law.
If an airline fails to respond, write again pointing out how happy you would be to ask the same questions of the local aviation authority.

@RobbieGoodwin No, it's not forbidden, see all the answers here! And since when is international law concerned with aviation regulations? Also: "it was your job to look them up before Asking on SE" No, this not required on this or any other Stack I know...

@RobbieGoodwin: By the simply laws of logic and common sense, what you are claiming cannot possibly be true. It would mean that we could never have new aircraft types, and would for all eternity be stuck with the aircraft we had in the 1920s. If you have a new aircraft type, the first flight of that flight will by definition be with a crew that has never flown that aircraft type before. Since we obviously do have new aircraft types (e.g. A380, A350XWB, B787, B737MAX), that clearly must be allowed somehow.

I apologize. I meant to say law ‘should’ forbid that.
Sorry I didn’t bother to add that if this is the airline’s first passenger flight, we might hope the passengers would not be paying public but people like factory, aviation authority, airline and travel-agency staff.
Not that their lives - which is the only point - are less important but can you not imagine the different media response if the thing crashed and burned?
BTW, “international law” consists solely of regulations including for aviation and shipping, trade and any other activity you could think of, including war.

@RobbieGoodwin: "if this is the airline’s first passenger flight, we might hope the passengers would not be paying public but people like factory, aviation authority, airline and travel-agency staff" – But then it's not a passenger flight. That's a training flight. Of course, both of the pilots in the video have had plenty of simulator sessions as well as training flights and check flights. But this is their first revenue flight with passengers, and there must by definition be at least one of those, for every new aircraft type. It is just not logically possible otherwise.

@RobbieGoodwin: Again, this doesn't actually have anything to do with aviation law, international law, or any law at all. It is a matter of basic logic and common sense. In any series of flights, there must have been a first flight, and on that first flight, the crew cannot, by definition, have flown that flight before.

Just to point out the obvious:

This got me thinking, does it ever happen that two pilots take their first passenger flight on a given type together

You don't even have to know anything about aviation to be able to answer this question. You can answer this question with common sense and basic logic:
If it's a new aircraft type, then by definition, nobody will ever have flown this particular aircraft type, which means that there must be at least one flight where all of the crew are taking their first flight. It is simply not possible otherwise.
Of course, all of them will have had simulator training on that aircraft type, and all of them will have training flights and checkout flights on that aircraft type, but just by the laws of basic logic, it is impossible for there not to be a flight where the whole crew has never flown a revenue flight with passengers before, simply because there always must be a first flight.

Until we get time machines, and visiting pilots from the future.

It is never “the first time”. What he is really saying is that after many hours of flying the aircraft (or an approved simulator) this is the first time doing a revenue flight with passengers. Previous flights would have been training flights.
When a new aircraft type is first introduced to an airline, it can be expected that the entire crew is doing their first revenue flight after training.
What is not expected is that the pilots announce it to the passengers. I would not advise doing that because the passengers might not understand, and it would put doubts in their minds, as it did for you.

It doesn't look like this was actually announced to the passengers of that flight, just made public after the fact to anyone watching the youtube video (I'm not saying you thought it was announced--just making this clear to anyone that doesn't watch the video).

[D]oes it ever happen that two pilots take their first passenger flight on a given type together [...]?

Yes, it does. In fact, it happened in exactly that flight you linked:

Found out that it was the first passenger flight for all of us pilots, but everything went perfect thanks to Scandinavian cooperation and teamwork.

(YouTube video description, emphasis mine)
There is no legal requirement to have any actual experience with passengers on that type. As long as all the pilots have successfully completed the type rating, which includes flight time in the actual aircraft or a level D simulator, and at least the PIC (pilot in command) has the full ATPL (Airline Transport Pilot Licence), which requires at least 1500 hours of flight experience (at least in Europe, not sure about US), there is nothing wrong with that.
Note that based on the other videos in that YouTube channel, the pilot seems to be type rated on the Airbus A330 as well, which is a very similar aircraft. An earlier video Learning To Fly The SAS A350 In Toulouse shows the transition training from the A330:

The one and only simulator session on the transition course from the A330 to the A350. It’s awesome plane.

In the USA, both have to have ATPL. It seems to be more a job market regulation than safety measure – there were too many pilots available, which meant especially on regional lines the wages were getting lower and the working conditions were poor, which might have resulted in safety issues if left unchecked, so they made it a bit harder to get in the right seat.

My answer considers EASA (European) rules.
As a general rule after a transition training in simulator, there is line-flight training in real aircraft. That is flying with (experienced) instructor, although there are passengers onboard. The length of this line-flight training depends on previous experience of the trainee, but it cannot be omitted. After line-flight training there is line check (usually again on actual normal commercial flight) after which the trainee can commence operations without instructor pilot onboard.
In Europe, there is a concept of "in-experienced" crew member. After line-flight training and successfully passed line check, the pilot is considered in-experienced for at least 100 flight hours and 10 sectors. The key idea here is that two crew in-experienced crew members cannot fly together.
So, before two pilots are allowed to operate together, both shall have at least around 120-150 hours of flying the type under their belts.
There are some deviations on this, and most notably airlines can temporarily ignore the in-experienced status when introducing new aircraft types into their fleet. But what they cannot do is skip mandatory line-flight training. It is not uncommon for airlines to buy training for their instructors from other airlines which already operate the type or have instructors from other airlines flying with their newly acquired planes with company pilots.
The case of A350 is little bit different, as it is considered as a "same type" as A330 and they have common type rating endorsement. Many of new A350 pilots are already A330 pilots they can skip some of the line-flight training involved. There is some sim training in between.
With my operator I had couple of flights with instructor when transitioning from A330 to A350. There was no separate line-check or in-experienced status, as I already was active with A330. So I guess in theory it might be that two A330 pilots can fly A350 together after transition course in simulator.
Partial source: https://www.easa.europa.eu/sites/default/files/dfu/Consolidated%20unofficial%20AMC%26GM_Annex%20III%20Part-ORO_0.pdf

For the very first flight of a new type at a given airline, obviously none of the pilots will have flown it with passengers before, though that crew will have undergone extensive training in sims and empty planes. However, that is a very rare case.
In general, a new pilot (either to that type or to the airline as a whole) will only be paired with certain more experienced pilots until their training is deemed complete, so you would never have two green pilots on the same plane.


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What license will one need to fly the Aeromobil flying car in 2022?
Aeromobil are launching their "flying car" in 2022, after successful test flights.
What kind of license / certification will be required to own / fly one of these? Presumably something less than a PPL, otherwise the barrier to entry will be too high.

You realise companies have been promising flying cars in a matter of months since about the 1960's? Flying cars give you a terrible car and an even worse aeroplane - I can't see they will ever be viable.

I would think the estimated $1,500,000 USD price would be the main barrier. If you can afford a multi million dollar aircraft, you can certainly afford the time and money required to obtain a pilot licence.

@Jamiec Fool on me for falling for that then :( You crushed my dreams :p

@Cloud In my humble opinion I do not think you'll find a single pilot who would want a flying car. If I had 1.5M I'd buy a nice car and a nice plane. Not a bad hybrid!

Molt Taylor's Aerocar was FAA certified in the 50s.  Like all the others, it was a crappy airplane and crappy car, rolled into one.  Image you'd bought an Aeromobil.  Do you think for a second you'd actually drive your delicate (by car standards) and expensive flower in traffic regularly, where the slightest fender bender grounds you?  You'd have to be outttayerfreakinmind.  Same with amphibious boats. Crappy boat, crappy car, all in one crappy package!  These things only work when the dual capability is so important that it's worth living with the limitations.

The first pal-v will only be 500k€. Still, a lot of money for a useless product.

So now in 2024, did anybody else read thru this and ask "hey, did I miss something?"

Short answer: You will almost certainly need a PPL at least.
On the subject of licensing for flying cars, nobody really knows, because no company has even come close to bringing one to market - and the term "bringing to market" for a flying car involves all the legalities of certification and licensing.

The U.S. based Chinese-owned firm Terrafugia and AeroMobil are also attempting to develop a two-seat flying car called the Transition, however, safety and development of the law for flying cars are just two of the challenges that must be met before they become a reality and not just a novelty. The Transition is designed to operate both on land and in the skies.

source: Aviation Law: An Analysis of the Development of Flying Cars for the 2020s Decade
In terms of aviation certification the Aeromobil specifications state

Aerospace: CS 23 Rev 5/ELA 1 (EU) & 14 CFR 23 Rev 5 (US)

That means for the US it is certified under Part 23 which will almost certainly need a minimum of a private pilots license. In the EU it is pretty much the same deal as many of the aviation standards/certifications around the world are based on ICAO norms.

Not that you asked for it, but in my opinion the only likely route to market for personal flying vehicles is ones where you're not doing the flying. One day I'm sure we'll have something like an automated Uber which ferries you A to B short distances. But something where you drive and fly is hugely unlikely.

At one point, before the acquisition by their Chinese parent company, Terrafugia had obtained an FAA waiver to allow a Light Sport license for the Transition, even though it was a couple hundred pounds over the normal weight limit.  That craft has been redesigned at least once since then, however, so who knows if that will still hold if/when they manage to sell any of them.

@ZeissIkon indeed, in researching some material for this answer I read all about Terrafugia and how they had this flying car which you didnt need any license at all! It was from 2014. Still no flying cars.

Yeah, "no license" was never going to happen, and pretty much everyone (except perhaps the aviation-ignorant public) knew it.  It could never have been close to Part 103 limits, or even European Ultrlight category, and still meet highway safety requirements (well, perhaps as a motorcycle, if they changed to a tricycle layout).

In the eyes of the FAA, it’s considered an Airplane, Single Engine Land category and class of aircraft. There is no license required to own the vehicle in the United States, save from registering it in your state of residence.
If you intend to operate it as an aircraft and serve as pilot in command (PIC), you’ll need to hold, at a minimum, a Recreational Pilot Certificate with Airplane Single Engine Land ratings. This would allow you to at least fly the thing, but imposes severe limitations on where and how you can travel in it. For any practical use of the AeroMobil as an aircraft, it is recommended that you hold at least a Private Pilot Certificate with Airplane Single Engine Land and Instrument Airplane ratings. This would allow for unrestricted operation of the aircraft as well as conducting Part 91 flight operation under IFR. You will also need to hold at least a Third Class Medical Certificate, or have held a valid FAA medical anytime after July 15, 2006 and conform to the guidelines of Part 68 for BasicMed.

Well, in that case, I can't see how it could ever replace the private car

It’s not like the idea of flying cars are anything new. They have existed since around the 1930s.  Every decade or so someone somewhere thinks they can reinvent the wheel.


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When was the last commercial hot air balloon fatality in the UK?
When was the last commercial hot air balloon fatality in the UK?

How are we defining "Commercial" here? Pilot in command is holder of a commercial license? Flight was with paying passengers? Some CAA/EASA/AAIB definition to do with the nature of the flight? I've made my best guess as to your intent in my answer.

All fatal accidents in the UK that occur with aircraft are investigated by the Air accidents Investigation Branch (AAIB), and their database is searchable. Their records go back as far as 1915 (although it is not certain that all have been digitalised).
Given the digital records which are available on their website, there have been no investigated reports listing fatalities involving a hot air balloon with the type of  flight identified as "Commercial Air Transport (Passenger)"

So this makes it the safest form of aviation in the UK, if you're a paying passenger that is

@Cloud I wouldnt jump to that conclusion - safety is a factor of passenger hours not absolute numbers.


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How common are diversions to high-latitude airports for intercontinental flights?
Comments to this question point out that diversions and emergency landings are not the same.
Many flights between Europe and North-America pass over (very) high latitudes and cold climates such as Greenland and northern Canada.  How common are diversions such as this one?  Or, more specifically, out of all scheduled passenger flights between Europe and North America, how many are diverted to high latitude airports?  For the purpose of this question, I am considering incidents where passengers were forced to leave the plane and change to one or more other planes, rather than a flight that lands and takes off again continuing to its final destination without passengers deplaning.

You may have luck by looking up incidents at the predetermined diversion airports.

Or you can search the NTSB accident database for specific airports/countries.

How far north does an airport have to be to qualify as "high latitude" by your standards?  Does Goose Bay count?  Does Gander?

@MichaelSeifert Good question.  It's not only about latitude.  I'd say anything very cold and very remote.

Very very uncommon. Goose Bay, Canada, is a diversion airport for US-Europe flights. If you search Aviation Herald for "goose", you will find about 2 to 3 flights divert there each year.

3 flights diverted in 2017:

Delta A330 Oct 20, engine problem
SAS A340 April 16, low cabin pressure
Air France A380 Sep 30, engine structural failure

2 flights diverted in 2016:

Virgin B787 Nov 22, engine oil leak  United B767 Sep 15, generator/APU failure

3 flights diverted in 2015:

American B757 Sep 30, electrical problem
Delta B767 July 31, generator failure
United B767 June 12, flight controls

2 flights diverted in 2014:

Delta B767 Aug 9, engine problem
Delta B767 May 1, engine shut down
In all these incidents except for 2, the report in Aviation Herald states a replacement aircraft was required. Sometimes the delay was 6 hours, sometimes the next day. In the 2 other incidents, it's unclear if a replacement aircraft was required or not, but in both cases maintenance was required, so at least a delay occurred.
This compares with a bird strike, or fumes/smoke in the cabin, almost daily somewhere. It's much rare than even lightning strikes, of which 25 were reported in 2017.

The OP asked specifically about Iqaluit.  These seem to be even less common; I count three diversions by major airlines to Iqaluit since 2008 (the recent SwissAir flight, a Delta flight flying AMS–SEA with unstowed spoilers, and an American flight from LHR–ORD with a medical emergency.)  Also, Goose Bay isn't that far north;  its latitude about the same as Manchester.

@MichaelSeifert. Fair points, though the OP does mention Greenland, and many of these diversions occurred when the aircraft was flying in the vicinity of Greenland. To some extent my answer was illustrating how they can get more info/answer their question. I updated the answer a bit because they also ask about incidents where the passengers have to change planes.